Impact of SARS-CoV-2 Infection on Cognitive Function: A Systematic Review

Yazen Alnefeesi; Ashley Siegel; Leanna M W Lui; Kayla M Teopiz; Roger C M Ho; Yena Lee; Flora Nasri; Hartej Gill; Kangguang Lin; Bing Cao; Joshua D Rosenblat; Roger S McIntyre

doi:10.3389/fpsyt.2020.621773

Impact of SARS-CoV-2 Infection on Cognitive Function: A Systematic Review

Front Psychiatry. 2021 Feb 10:11:621773. doi: 10.3389/fpsyt.2020.621773. eCollection 2020.

Authors

Yazen Alnefeesi¹, Ashley Siegel¹, Leanna M W Lui¹, Kayla M Teopiz¹, Roger C M Ho², Yena Lee¹, Flora Nasri¹, Hartej Gill¹, Kangguang Lin^{3

4}, Bing Cao⁵, Joshua D Rosenblat^{1

6}, Roger S McIntyre^{1

6

7

8}

Affiliations

¹ Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada.
² Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
³ Department of Affective Disorder, the Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou Medical University, Guangzhou, China.
⁴ Laboratory of Emotion and Cognition, the Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou Medical University, Guangzhou, China.
⁵ Key Laboratory of Cognition and Personality, Faculty of Psychology, Ministry of Education, Southwest University, Chongqing, China.
⁶ Department of Psychiatry, University of Toronto, Toronto, ON, Canada.
⁷ Department of Pharmacology, University of Toronto, Toronto, ON, Canada.
⁸ Brain and Cognition Discovery Foundation, Toronto, ON, Canada.

Abstract

The prevalence and etiology of COVID-19's impact on brain health and cognitive function is poorly characterized. With mounting reports of delirium, systemic inflammation, and evidence of neurotropism, a statement on cognitive impairment among COVID-19 cases is needed. A substantial literature has demonstrated that inflammation can severely disrupt brain function, suggesting an immune response, a cytokine storm, as a possible cause of neurocognitive impairments. In this light, the aim of the present study was to summarize the available knowledge of the impact of COVID-19 on cognition (i.e., herein, we broadly define cognition reflecting the reporting on this topic in the literature) during the acute and recovery phases of the disease, in hospitalized patients and outpatients with confirmed COVID-19 status. A systematic review of the literature identified six studies which document the prevalence of cognitive impairment, and one which quantifies deficits after recovery. Pooling the samples of the included studies (total sample n = 644) at three standards of quality produced conservative estimates of cognitive impairment ranging from 43.0 to 66.8% prevalence in hospitalized COVID-19 patients only, as no studies which report on outpatients met criteria for inclusion in the main synthesis. The most common impairment reported was delirium and frequent reports of elevated inflammatory markers suggest etiology. Other studies have demonstrated that the disease involves marked increases in IL-6, TNFα, and IL-1β; cytokines known to have a profound impact on working memory and attention. Impairment of these cognitive functions is a characteristic aspect of delirium, which suggests these cytokines as key mediators in the etiology of COVID-19 induced cognitive impairments. Researchers are encouraged to assay inflammatory markers to determine the potential role of inflammation in mediating the disturbance of cognitive function in individuals affected by COVID-19.

Keywords: COVID-19; brain health; cognitive function; cytokines; delirium; depression; neuroinflammation; neurotropism.

Publication types

Systematic Review